Thermal printer or thermal copier: which file to use for each
Reviewed on October 16, 2026
Both machines end up on the same carbon paper, but one prints straight from a computer or phone and the other copies a printed original. The file you need changes.
Thermal stencil printer
Prints from a computer or a phone app straight onto stencil paper. Portable ones work at 203 dpi and some at 300; the printhead is usually as wide as an A4 or Letter sheet.
Thermal copier
Copies an original on plain paper: you print the design on a laser printer (or draw it) and the machine transfers it to thermal paper with heat. Quality depends on the original: print it at 600 dpi in solid black, with no greys.
Which file to use
In all three cases the content is 1-bit: black or nothing.
- Thermal printer from a phone app: 1-bit PNG at the printer’s resolution, with its dpi embedded so it prints at real size.
- Thermal printer from a computer: real-size PDF, printed at 100 %.
- Thermal copier: 600 dpi PDF printed on a laser printer, then copied.
What doesn’t change
Lines thick enough, large blacks hollowed and light screened shading: what makes a stencil transfer well is the same on both machines.